Antacids are used to treat ulcers and for neutralizing an excess of acid such as a large production of gastric acid. The development of antacid therapy goes towards a use of large doses at frequent dosages to keep the amount of free acid in the stomach low during all the day and night. (Fordtran J et al.: N. Engl. J. Med. 288: 923-928, 1973; Fordtran J. et al.: N. Engl J. Med. 274; 921-927, 1966; Deering T, Mlagelada J-R: Gastroenterology 73: 11-14, 1977).
The requirements set forth on a complete antacid agent are i.a. that it shall have a high neutralizing capacity, rapid reaction with the hydrochloric acid of the gastric juice, have a maximal buffer capacity at pH 3 to 5, not give an increase of the pH of the stomach contents of above pH 7 at overdosage, not develop carbon dioxide in contact with hydrochloric acid, not be absorbed as such or in ion form, and, in other respects, be pharmacologically inactive and be well tolerated.
The antacid compounds which are normally used are the following: